The Colours of Autumn
Posted by Phytopath on Mar 18, 2011
The Southern Hemisphere has moved into autumn. Soon the deciduous trees will start to colour and fall.
Just how and why do they produce such beautiful bonfire colours of yellow, gold, orange, rust and scarlet?
For gardeners who live in temperate regions with four distinct seasons, the beautiful colours of deciduous trees herald the coming of winter.
But the days are still warm and the nights are cooling rapidly: a sure fire recipe for taking successful stem cuttings.
The first six weeks of autumn are a great time to take stem cuttings, while the plant is still manufacturing carbohydrates and storing them for the winter rest.
But then, the leaves will begin to put on a brilliant display of colour before falling like confetti at a wedding.
So why do the leaves fall? Why not stay on the branch just like evergreen trees?
Firstly, the role of the leaves is to supply nourishment to the rest of the tree through the process of photosynthesis.
The leaves do this by using raw materials: carbon dioxide from the air, water from the soil and the energy from sunlight.
The water is taken up by the roots through a network of vessels called ‘xylem’. Think of them as a super highway with many lanes, stretching for many kilometres. The traffic on the highway is traveling in one direction only. One side of the road heading out of the city and the other side of the road the traffic is heading toward the city.
If you have that picture in your mind, you can visualize the xylem vessels traveling from the roots in the soil, all the way up the trunk of the tree and into the veins of the leaves.
It is here in the centre of the leaf tissue called mesophyll, where the water combines with carbon dioxide (which has entered through tiny openings in the leaves, called stomata) through the process of photosynthesis, to form carbohydrates (glucose).
Once the leaves have manufactured their food source, they need to distribute that food to the rest of the plant. So the glucose is now shipped back on the super highway through vessels called ‘phloem’. Think of xylem and phloem as the name of the business trucks that are transporting goods up and down the highway.
I still haven’t explained the process of colour change in the leaves from green to ‘autumn tones’ but I’m getting to that.
Within the chloroplasts (in the leaves) are molecules of colouring agents called chlorophyll, carotenes and xanthophylls. These molecules are in the leaves at other times of the year but the intense green pigment of chlorophyll tends to hide them.
As autumn approaches, a hormone is released within the plant (gee they are clever) to signal the change in temperature and sunlight hours.
The chlorophyll content of the leaves decreases causing leaves to lose their green colour, but reveal the yellow tones that already exist in the leaves.
By the way, carotene is also responsible for the yellow colour of bananas and the orange colour of carrots, pumpkin and sweet potato.
But what about the beautiful red leaf colour of trees like maple?
The red pigment does not already occur in the leaves like the yellow pigment. The red and scarlet colouring of deciduous leaves only occurs during autumn.
The intense red is produced by a pigment called anthocyanin. This pigment is also found in plants like beetroot, radishes (red ones) and hyacinths.
Trapped glucose is responsible for producing the vivid reds of autumn leaves.
When photosynthesis slows down and then ceases, the flow of water from the xylem vessels and glucose from the phloem vessels comes to an end.
The hormone that I mentioned earlier, called abscisic acid, is mobilised and travels to the area where the leaf stem (called a petiole), joins the branch. This area is called the abscission layer. It is here that the flow of water and glucose is blocked. (Kind of like a pile- up on the highway that blocks all traffic movement).
When this happens, some glucose usually remains trapped in the mesophyll cells. A combination of bright sunlight, cool night temperatures and trapped glucose, make a wonderful recipe for scarlet and red autumn leaves.
And what a wonderful sight, unless of course there is an early frost which will turn the leaves dry and brown.
Time for Tea
Posted by Phytopath on Mar 6, 2011
Have you ever considered growing your own tea plant?
Regular black or green tea is made from the harvested and dried leaves of the Camellia sinensis plant.
You may be lucky enough to live in an area where this plant will grow well, but most people don’t.
An alternative to regular tea is herbal tea.
Now before you start screwing your face up and saying yuk, there are some wonderful combinations of flavours that will delight the taste buds.
Not all herbal teas taste like earth.
Consider planting a tea garden. That way you will have fresh material whenever you feel like making a cup of tea and scones (or biscuit), plus, they are caffeine free and generally low in tannins.
Plant your herbs where they will receive sufficient sunlight, to encourage the aromatic oils that give the leaves their distinctive flavour.
A well drained soil is also a must, whether the plants are grown in the ground or in a pot or tub. Provide healthy organic soil to encourage plenty of leaf growth for picking.
It is also a good idea to place your tea garden close to the kitchen for easy access. You don’t want to have to walk to the bottom of the garden just to collect material for a cup of tea.
Here are some plant suggestions to start your tea garden. 
Lemon verbena (Aloysia triphylla) as the name suggests, has a lemon flavour. Just three freshly picked leaves in a cup of boiling water will give you a wonderfully refreshing drink.
The plant needs a warm sheltered position and can grow to two or three metres tall. Prune the bush hard at the end of winter to encourage fresh new growth and help prevent the plant from becoming straggly.
Pineapple sage (Salvia elegans syn. S. rutilans) looks wonderful in the garden with its bright red flowers. The leaves have a distinct pineapple scent and make a fragrant cup of tea. They can also be used in fruit punch and fruit salad. Give the plant plenty of water during hot weather.
Lemon balm (Melissa officinalis) is another plant that has a delicate lemon scent and flavour. Use the leaves fresh as they don’t retain their flavour when dried. It is said that drinking Lemon balm tea will extend your lifespan and soothe indigestion and nausea. This plant will also grow in light shade.
Bergamot (Monarda didyma) has attractive red flowers in summer and both the leaves and flowers can be used in teas. The common name was given to the plant because of the likeness in scent to the Bergamot Orange (Citrus bergamia). Use the leaves to flavour drinks, salads and stuffing. The plant is regularly listed as a perennial but in my hot climate it behaves like an annual, dying after just one year.
Mint (Mentha spp.) comes in many flavours and aromas. Try a chocolate mint tea or a refreshing Moroccan mint tea, or how about a chocolate and apple mint tea? Perhaps the common mint, spearmint or peppermint are more to your liking. To prevent the plants from spreading too far, grow them in pots.
The above suggestions are just a small sampling of herbal teas with a pleasant flavour. You can use them individually or make a blend.
Use about one teaspoon of freshly picked leaves and place in a cup. Cover with boiling water and allow to infuse for about five minutes. It is best not to add milk.
